An administrator examines the following routing table output on a Cisco router:
text
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
O 10.15.0.0/16 [110/20] via 192.168.1.1, 00:10:22, GigabitEthernet0/0
D 10.15.10.0/24 [90/307200] via 192.168.2.1, 00:05:14, GigabitEthernet0/1
S 10.15.10.128/25 [1/0] via 192.168.3.1, 01:12:05, GigabitEthernet0/2
C 10.15.10.0/28 is directly connected, GigabitEthernet0/3
Which two statements regarding route selection and routing table components in this output are correct?
- Packets destined for host 10.15.10.130 are forwarded out interface GigabitEthernet0/2 because the subnet mask /25 provides the longest matching prefix for this destination.Cevap
- BPackets destined for host 10.15.10.10 will be forwarded to 192.168.3.1 because the static route has a lower administrative distance than all dynamic routing protocols.
- The bracketed notation [90/307200] in the EIGRP entry indicates an administrative distance of 90 and a routing metric of 307200.Cevap
- DPackets destined for host 10.15.10.5 will be sent via 192.168.1.1 because OSPF is evaluated before connected routes in routing table lookup operations.
Cevap
The two correct statements are that packets destined for host 10.15.10.130 are forwarded out interface GigabitEthernet0/2 due to longest prefix match (/25), and that the bracketed notation [90/307200] represents an administrative distance of 90 and a metric of 307200.
Longest prefix match is the primary rule for IP packet forwarding. Destination 10.15.10.130 matches 10.15.10.128/25 with a 25-bit mask, which is longer than /24 or /16, causing forwarding via GigabitEthernet0/2. Additionally, standard Cisco routing table format displays administrative distance first and metric second inside square brackets, making [90/307200] represent an AD of 90 and a metric of 307200.
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Routing Table Lookup Logic & Component Interpretation